title: Preosteoblast production 55 hours after a 12.5-day spaceflight on Cosmos 1887.
abstract: The influence of 12.5 days of spaceflight and a 55 h stressful recovery period (at 1 g) on fibroblastlike osteoblast precursor cells was assessed in the periodontal ligament (PDL) of rats that were 91 days old at launch. Nuclear morphometry was used as a marker for precursor cell differentiation in 3 microns sections cut in the midsagittal plane from the maxillary first molar. According to nuclear volume, cells were classified as preosteoblasts (C + D cells, greater than or equal to 120 microns 3) and less differentiated progenitor cells (A + A' cells, 40-79 microns 3). Compared with synchronous controls (simulated flight conditions), the 55 h postflight recovery period at 1 g resulted in a 40% decrease in the A + A' cell population, a 42% increase in the C + D cells, and a 39% increase in the number of PDL fibroblastlike cells near the bone surface. These results are consistent with a postflight osteogenic response in PDL. This recovery response occurred despite physiological stress in the flight animals that resulted in a highly significant (P less than or equal to 0.001) increase in adrenal weight. The data suggest that after spaceflight there is a strong and rapid recovery mechanism for osteoblast differentiation that is not suppressed by physiological stress.
authors.affiliation: Department of Orthodontics, Indiana University School of Dentistry, Indiana University School of Medicine, Indianapolis 46202.
authors.forename: L P
authors.initials: LP
authors.lastname: Garetto
authors.forename: M R
authors.initials: MR
authors.lastname: Gonsalves
authors.forename: E R
authors.initials: ER
authors.lastname: Morey
authors.forename: G
authors.initials: G
authors.lastname: Durnova
authors.forename: W E
authors.initials: WE
authors.lastname: Roberts
mesh_terms: D000818:Animals; D001835:Body Weight; D001846:Bone Development / Q000502:physiology*; D002452:Cell Count; D002454:Cell Differentiation; D005347:Fibroblasts / Q000166:cytology; D007700:Kinetics; D008297:Male; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013026:Space Flight; D013234:Stem Cells / Q000166:cytology / Q000502:physiology*; D014893:Weightlessness